Blender model deformation when moving with bone
Don't parent With Automatic Weight, because it will give influence to several bones and your helmet will bend, instead parent to &gt; Bone: Select the helmet, shift select the armature, then switch the armature to Pose mode, you'll see that the helmet is still selected, and press ctrlP &gt; Bone. Parent With Automatic Weight is good for organic objects, but for machines, robots, etc, use a direct parent to bone.